function IETester(userAgent){
    var UA =  userAgent || navigator.userAgent;
    if(/msie/i.test(UA)){
        return UA.match(/msie (\d+\.\d+)/i)[1];
    }else if(~UA.toLowerCase().indexOf('trident') && ~UA.indexOf('rv')){
        return UA.match(/rv:(\d+\.\d+)/)[1];
    }
    return false;
}